EP0572368A2 - Phase discriminating capacitive array sensor system - Google Patents

Phase discriminating capacitive array sensor system Download PDF

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Publication number
EP0572368A2
EP0572368A2 EP93850112A EP93850112A EP0572368A2 EP 0572368 A2 EP0572368 A2 EP 0572368A2 EP 93850112 A EP93850112 A EP 93850112A EP 93850112 A EP93850112 A EP 93850112A EP 0572368 A2 EP0572368 A2 EP 0572368A2
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EP
European Patent Office
Prior art keywords
sensor
phase
adjustment made
voltage
sensor signal
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93850112A
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German (de)
French (fr)
Inventor
John M. Vranish
Wadi Rahim
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US Department of Health and Human Services
National Aeronautics and Space Administration NASA
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US Department of Health and Human Services
National Aeronautics and Space Administration NASA
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Publication of EP0572368A2 publication Critical patent/EP0572368A2/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/24—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance
    • G01D5/2405—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying capacitance by varying dielectric
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/945—Proximity switches
    • H03K17/955—Proximity switches using a capacitive detector
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
    • H03K17/96—Touch switches
    • H03K17/962—Capacitive touch switches
    • H03K17/9622—Capacitive touch switches using a plurality of detectors, e.g. keyboard

Definitions

  • This invention relates to a phase discriminating capacitive sensor array system producing sensor signals which are phase and amplitude controlled based on a frequency reference provided by a single frequency stabilized oscillator.
  • Capacitive sensor arrays are used in industry to sense the proximity of an object.
  • capacitive sensor arrays have been provided with a circuit having a number of free running oscillators, each corresponding to one of a number of sensor elements in the array provided to sense the object.
  • the corresponding oscillator experienced a change in frequency.
  • the conventional circuit recognized the object based on a change in capacitance caused by the change in the frequency of the free running oscillator.
  • each of the free running oscillators provided for each sensor element is susceptible to being "pulled” as described above, the sensors must be placed far enough apart to ensure that the free running oscillators in each sensor do not interact, couple and lock on to each other (cross talk).
  • the range and sensitivity of the conventional system has been limited by a significant degree.
  • pixelized imaging has not been possible due to the lack of proximal collocation of the sensor elements.
  • Another disadvantage of the conventional capacitive sensor array system has been that the multiple free running oscillators have required that relatively wide band widths be provided for the sensor electronics input bandwidths. These wide bandwidths have resulted in increased noise and a decreased signal-to-noise ratio. As a result of this disadvantage as well, the range and sensitivity of the conventional system have been limited by a significant degree.
  • Another object of the invention is to provide a capacitive sensor array system with narrow band filtering and resulting minimal noise and high signal to noise ration, without frequency drift, and which can detect the proximity, closing speed and edges of an object sensed by the sensor elements.
  • phase discriminating capacitive sensor array system which provides a single free running oscillator which is stabilized to a fixed frequency.
  • Multiple sensor elements are provided for which the single oscillator is a frequency reference.
  • Multiple phase control units corresponding to the multiple sensor elements, are also provided which control the phase and amplitude of the sensor signals from the sensor elements to stay identical to that of the frequency reference, and which determine the proximity of an object by measuring the adjustment made to the sensor signals.
  • the phase control units may also determine the closing speed of the object based on the rate of change of the adjustment, and the edges of the object based on a sudden reduction in the adjustment made.
  • FIG. 1 shows an overall block diagram of the phase discriminating capacitive sensor array system of the invention, having an array 2 comprised of a common shield 4 on which sensor elements 1-N are provided, and a common ground 6.
  • the shield 4 and sensor elements 1-N each output a sensor signal to N phase control units 8, 10, 12, 14 and 16-18, respectively.
  • Each phase control unit maintains the phase and amplitude of the sensor signal from each of the sensor elements 1-N, in accordance with a frequency reference provided by a crystal controlled oscillator 20.
  • the oscillator is frequency stabilized to a common frequency shared by the shield 4, ground 6 and sensor elements 1-N.
  • the phase control units each produce an output signal (denoted shield output, and outputs 1-N). These output signals represent the voltage required to keep the sensor signals provided by the corresponding sensor elements 1-N at the same frequency, phase and amplitude.
  • FIG. 2 is a block circuit diagram of any one of the phase control units 8, 10, 12, 14, and 16-18.
  • the phase control unit 10 which controls the sensor signal from sensor element 1, and produces output 1, is shown.
  • the frequency reference from the oscillator 20 is passed through a conventional phase shifter 22 and then through a conventional gain control 24.
  • the output of the gain control drives a conventional resistor 26 connected to the sensor element 1 and the input of a conventional buffer amplifier filter 28.
  • the buffer amplifier filter 28 includes a narrow bandpass filter at the frequency reference in order to remove a significant amount of the ambient noise. Since the frequency is fixed, the bandwidth is only as wide as the motion of the object sensed by sensor 1, for example, 2 hertz. The narrow band filtering is possible because the sensor element simply appears as part of an impedance in a transmission line. This filtering occurs upon input of the sensor signal to the phase control unit.
  • the output of the buffer amplifier filter 28 drives a conventional phase comparator 30 and level comparator 32.
  • the outputs from these comparators are input to a controller 34, which drives the phase shifter 22 and gain control 24 to maintain the signal from sensor 1 identical to the frequency reference from the oscillator 20.
  • the sensor element 1 When the sensor element 1 senses an object, its change in capacitance changes the amount of adjustment required to be made by the controller 34 to the sensor signal. This change in the required amount of adjustment is reflected by a corresponding change in voltage in the output signal (output 1) from the controller 34. Thus, the change in voltage in output 1 indicates the proximity of the object sensed by sensor 1. Also, the rate of change in this voltage, which reflects the rate of change in the required amount of adjustment, thus indicates the closing speed of the object.
  • FIG. 3 is the flow chart of the control performed by the controller 34.
  • the controller voltage V AMP used to set the initial voltage at the sensor element
  • the controller voltage V PH used to set the initial phase at the sensor element
  • the change in voltage ⁇ V, and the change in phase-induced voltage ⁇ PH which are expected to result when the sensor element encounters the object, are initialized based on an initial estimate for these values as expected.
  • the amplitude AMP of the sensor signal is compared to the controller voltage V AMP which indicates the initial sensor voltage.
  • V AMP exceeds V AMP
  • the controller voltage V AMP is adjusted in step 40 by adding the change in voltage ⁇ V of the sensor signal caused by the capacitance change in the sensor element when the sensor element senses an object. If, however, AMP does not exceed V AMP then V AMP is adjusted in step 42 by subtracting the change in voltage ⁇ V.
  • step 44 the phase PH of the sensor signal is compared to controller voltage V PH (which indicate the initial sensor phase). If PH exceeds V PH then the controller voltage V PH is adjusted in step 46 by adding the phase induced voltage change ⁇ PH. If, however, PH does not exceed V PH then V PH is adjusted in step 48 by subtracting ⁇ PH.
  • step 50 ⁇ V and ⁇ PH are then recomputed based on a software search which implements in iteration to converge these values to within a specified range.
  • the specified range takes into account the distance and speed of the object.
  • step 52 the controller voltages V AMP and V PH are output as the output signal indicating the proximity and closing speed of the object. Control then returns to step 38, and the above described steps 38-52 are continually repeated as appropriate.
  • the sensor elements 1-N can be placed as closely together as desired, so that cross talk between the sensor elements is eliminated.
  • the proximity and closing speed are measured by the adjustment made to the sensor signals for each sensor element, instead of by measuring an effect on a free running oscillator for each sensor element, as in the conventional capacitive sensor array system described above in the Background of the Invention.
  • multiple free-running oscillators do not need to be provided corresponding to the multiple sensors, and cross-talk is therefore not a problem.
  • the sensor elements can be placed as closely to the shields as desired in a "capaciflector" system, as described above.
  • the sensor elements 1-N can be provided on the single shield 4 as shown in FIG. 2.
  • the output signals which provide the voltage indicative of the proximity and closing speed of the object can be provided to a robot controller which interprets and acts on the proximity and speed information accordingly.
  • a pixelized image of the object can be produced using the output signals (shield output and outputs 1-N).
  • the edges of the object can be detected based on a sudden decrease in the voltages indicated by the output signals, which indicates a fall off of the amount of adjustment applied to the sensor signals for the sensor elements sensing the object at the edge.
  • output signals providing the voltages indicative of the proximity, closing speed and edges of an object can be utilized in a number of applications including but not limited to the robotics sensing and pixelized imaging described above.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electronic Switches (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

Description

    Background of the Invention Field of the Invention
  • This invention relates to a phase discriminating capacitive sensor array system producing sensor signals which are phase and amplitude controlled based on a frequency reference provided by a single frequency stabilized oscillator.
    • Description of the Related Art
  • Capacitive sensor arrays are used in industry to sense the proximity of an object. Conventionally, capacitive sensor arrays have been provided with a circuit having a number of free running oscillators, each corresponding to one of a number of sensor elements in the array provided to sense the object. When one of the sensors detected the object (was "pulled") the corresponding oscillator experienced a change in frequency. The conventional circuit recognized the object based on a change in capacitance caused by the change in the frequency of the free running oscillator. An example of such a conventional capacitive sensor array system is fully described in An In-situ Evaluation of a Capacitive Sensor Based Safety System for Automotive Manufacturing Environment, by Don L. Millard, published in Robots 13, Conference Proceedings, SME/RI, May 7-11, 1989.
  • In the conventional system described above, however, because each of the free running oscillators provided for each sensor element is susceptible to being "pulled" as described above, the sensors must be placed far enough apart to ensure that the free running oscillators in each sensor do not interact, couple and lock on to each other (cross talk). As a result, the range and sensitivity of the conventional system has been limited by a significant degree. Also, pixelized imaging has not been possible due to the lack of proximal collocation of the sensor elements.
  • Another disadvantage of the conventional capacitive sensor array system has been that the multiple free running oscillators have required that relatively wide band widths be provided for the sensor electronics input bandwidths. These wide bandwidths have resulted in increased noise and a decreased signal-to-noise ratio. As a result of this disadvantage as well, the range and sensitivity of the conventional system have been limited by a significant degree.
  • Still another disadvantage of the conventional system has been that frequency drift could not be prevented; since the system depended on "pulling" the oscillator, frequency stabilized oscillators, such as common crystal controlled oscillators, could not be provided. As a result, frequency drift has posed a major problem in the past, particularly due to increases in heat and temperature.
  • An additional disadvantage potentially present in a conventional capacitive sensor array system is that "capaciflector" sensors could not be easily employed. In a capaciflector sensor system individual shields are employed for each sensor element, as disclosed in USP No. 5,166,679. As a result, a capaciflector system using multiple free running oscillators must have sufficient spacing to prevent cross talk with the shields.
    • Summary of the Invention
  • It is an object of the invention to provide a capacitive sensor array system without limitation on the proximity of adjacent sensor elements with capaciflector shields, without cross talk between the sensor elements, and with a pixelized imaging capability.
  • Another object of the invention is to provide a capacitive sensor array system with narrow band filtering and resulting minimal noise and high signal to noise ration, without frequency drift, and which can detect the proximity, closing speed and edges of an object sensed by the sensor elements.
  • The above and other objects can be obtained by a phase discriminating capacitive sensor array system which provides a single free running oscillator which is stabilized to a fixed frequency. Multiple sensor elements are provided for which the single oscillator is a frequency reference. Multiple phase control units, corresponding to the multiple sensor elements, are also provided which control the phase and amplitude of the sensor signals from the sensor elements to stay identical to that of the frequency reference, and which determine the proximity of an object by measuring the adjustment made to the sensor signals. The phase control units may also determine the closing speed of the object based on the rate of change of the adjustment, and the edges of the object based on a sudden reduction in the adjustment made.
    • Brief Description of the Drawings
    • FIG. 1 is an overall block diagram of the phase discriminating capacitive sensor array system of the present invention;
    • FIG. 2 is a block circuit diagram of a phase control unit shown in FIG. 1; and
    • FIG. 3 is a flow chart of the control performed by the controller shown in FIG. 2.
    Detailed Description of the Preferred Embodiments
  • FIG. 1 shows an overall block diagram of the phase discriminating capacitive sensor array system of the invention, having an array 2 comprised of a common shield 4 on which sensor elements 1-N are provided, and a common ground 6. The shield 4 and sensor elements 1-N each output a sensor signal to N phase control units 8, 10, 12, 14 and 16-18, respectively. Each phase control unit maintains the phase and amplitude of the sensor signal from each of the sensor elements 1-N, in accordance with a frequency reference provided by a crystal controlled oscillator 20. The oscillator is frequency stabilized to a common frequency shared by the shield 4, ground 6 and sensor elements 1-N. The phase control units each produce an output signal (denoted shield output, and outputs 1-N). These output signals represent the voltage required to keep the sensor signals provided by the corresponding sensor elements 1-N at the same frequency, phase and amplitude.
  • FIG. 2 is a block circuit diagram of any one of the phase control units 8, 10, 12, 14, and 16-18. For example, the phase control unit 10, which controls the sensor signal from sensor element 1, and produces output 1, is shown. The frequency reference from the oscillator 20 is passed through a conventional phase shifter 22 and then through a conventional gain control 24. The output of the gain control drives a conventional resistor 26 connected to the sensor element 1 and the input of a conventional buffer amplifier filter 28.
  • The buffer amplifier filter 28 includes a narrow bandpass filter at the frequency reference in order to remove a significant amount of the ambient noise. Since the frequency is fixed, the bandwidth is only as wide as the motion of the object sensed by sensor 1, for example, 2 hertz. The narrow band filtering is possible because the sensor element simply appears as part of an impedance in a transmission line. This filtering occurs upon input of the sensor signal to the phase control unit.
  • The output of the buffer amplifier filter 28 drives a conventional phase comparator 30 and level comparator 32. The outputs from these comparators are input to a controller 34, which drives the phase shifter 22 and gain control 24 to maintain the signal from sensor 1 identical to the frequency reference from the oscillator 20.
  • When the sensor element 1 senses an object, its change in capacitance changes the amount of adjustment required to be made by the controller 34 to the sensor signal. This change in the required amount of adjustment is reflected by a corresponding change in voltage in the output signal (output 1) from the controller 34. Thus, the change in voltage in output 1 indicates the proximity of the object sensed by sensor 1. Also, the rate of change in this voltage, which reflects the rate of change in the required amount of adjustment, thus indicates the closing speed of the object.
  • FIG. 3 is the flow chart of the control performed by the controller 34. First, in step 36, the controller voltage VAMP (used to set the initial voltage at the sensor element) and the controller voltage VPH (used to set the initial phase at the sensor element) are initialized. Also, the change in voltage ΔV, and the change in phase-induced voltage ΔPH, which are expected to result when the sensor element encounters the object, are initialized based on an initial estimate for these values as expected. Next, in step 38, the amplitude AMP of the sensor signal is compared to the controller voltage VAMP which indicates the initial sensor voltage. If AMP exceeds VAMP, then the controller voltage VAMP is adjusted in step 40 by adding the change in voltage ΔV of the sensor signal caused by the capacitance change in the sensor element when the sensor element senses an object. If, however, AMP does not exceed VAMP then VAMP is adjusted in step 42 by subtracting the change in voltage ΔV.
  • In step 44, the phase PH of the sensor signal is compared to controller voltage VPH (which indicate the initial sensor phase). If PH exceeds VPH then the controller voltage VPH is adjusted in step 46 by adding the phase induced voltage change ΔPH. If, however, PH does not exceed VPH then VPH is adjusted in step 48 by subtracting ΔPH.
  • In step 50, ΔV and ΔPH are then recomputed based on a software search which implements in iteration to converge these values to within a specified range. Ideally, the specified range takes into account the distance and speed of the object. In step 52, the controller voltages VAMP and VPH are output as the output signal indicating the proximity and closing speed of the object. Control then returns to step 38, and the above described steps 38-52 are continually repeated as appropriate.
  • As a result of maintaining the sensor signals to be identical to the frequency reference provided by the oscillator 20, the sensor elements 1-N can be placed as closely together as desired, so that cross talk between the sensor elements is eliminated. The proximity and closing speed are measured by the adjustment made to the sensor signals for each sensor element, instead of by measuring an effect on a free running oscillator for each sensor element, as in the conventional capacitive sensor array system described above in the Background of the Invention. Thus, multiple free-running oscillators do not need to be provided corresponding to the multiple sensors, and cross-talk is therefore not a problem.
  • Another advantage of maintaining the sensor signals to be identical to the frequency reference is that the sensor elements can be placed as closely to the shields as desired in a "capaciflector" system, as described above. Thus, the sensor elements 1-N can be provided on the single shield 4 as shown in FIG. 2.
  • Also, because a narrow band bandpass filter is provided at the frequency reference in the buffer amplifier filter 28, noise is greatly reduced and the signal to noise ratio is improved, thus improving the sensor range and sensitivity.
  • Additionally, the output signals which provide the voltage indicative of the proximity and closing speed of the object can be provided to a robot controller which interprets and acts on the proximity and speed information accordingly. Also, as a result of maintaining the sensor signals to be identical to the frequency reference so that the sensor elements 1-N can be placed closely together, a pixelized image of the object can be produced using the output signals (shield output and outputs 1-N). Also, the edges of the object can be detected based on a sudden decrease in the voltages indicated by the output signals, which indicates a fall off of the amount of adjustment applied to the sensor signals for the sensor elements sensing the object at the edge.
  • It should be noted that the output signals providing the voltages indicative of the proximity, closing speed and edges of an object, can be utilized in a number of applications including but not limited to the robotics sensing and pixelized imaging described above.

Claims (10)

  1. A phase discriminating capacitive sensor array system for detecting an object, comprising:
    (a) a capacitive sensor array having sensor elements to sense the object, each sensor element producing a sensor signal;
    (b) a frequency stabilized oscillator providing a frequency reference; and
    (c) phase control means for controlling the phase and amplitude of each sensor signal, and adjusting each sensor signal to correspond to the frequency reference provided by said frequency stabilized oscillator.
  2. A phase discriminating capacitive sensor array system according to claim 1, wherein
       said phase control means produces an output signal indicating the proximity of the object based on the adjustment made to each said sensor signal by said phase control means, and/or the closing speed of the object based on a rate of change of the adjustment made to the sensor signal.
  3. A phase discriminating capacitive sensor array system according to claim 1, wherein
       said phase control means produces an output signal indicating an edge of the object based on a sudden decrease in the adjustment made to the sensor signal.
  4. A phase discriminating capacitive sensor array system according to claim 1, wherein said capacitive sensor array comprises a common shield on which said sensor elements are provided.
  5. A method of detecting an object, comprising the steps of:
    (a) sensing the object with multiple capacitive sensor elements and producing a sensor signal for each of the sensor elements;
    (b) providing a common frequency reference for each of the sensor elements; and
    (c) adjusting the sensor signal from each of the sensor elements to correspond to the common frequency reference.
  6. A method according to claim 5, further comprising the step of:
       (d) producing an output signal indicating a proximity of the object based on the adjustment made to each said sensor signal, and/or the closing speed of the object based on a rate of change of the adjustment made to the sensor signal.
  7. A method according to claim 5, further comprising the step of:
       (d) producing an output signal indicating an edge of the object based on a sudden decrease in the adjustment made to the sensor signal.
  8. A method according to claim 5, wherein step (c) comprises:
       adjusting a voltage indicating initial sensor voltage by a voltage change induced by an amplitude change caused by sensing the object, and adjusting a voltage indicating initial sensor voltage by a voltage change induced by a phase change caused by sensing the object.
  9. A method according claim 8, wherein step (d) comprises:
       producing an output signal indicating the proximity of the object based on the adjustment made to each said sensor signal based on the adjusted voltage, and/or the closing speed of the object-based on a rate of change of the adjustment made to the sensor signal.
  10. A method according to claim 8, wherein step (d) comprises:
       producing an output signal indicating an edge of the object based on a sudden decrease in the adjustment made to the sensor signal based on the adjusted voltage.
EP93850112A 1992-05-28 1993-05-24 Phase discriminating capacitive array sensor system Withdrawn EP0572368A2 (en)

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US889577 1992-05-28
US07/889,577 US5214388A (en) 1992-05-28 1992-05-28 Phase discriminating capacitive array sensor system

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0838737A1 (en) * 1996-10-25 1998-04-29 Asulab S.A. Means for identifying a manual action on a surface, in particular for a time piece
EP0984329A2 (en) * 1998-09-04 2000-03-08 Canon Kabushiki Kaisha Position detection apparatus having a plurality of detection sections, and exposure apparatus
WO2003106936A2 (en) * 2002-06-13 2003-12-24 Environment One Corporation Scanning capacitive array sensor and method

Families Citing this family (62)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5321366A (en) * 1992-08-31 1994-06-14 Murata Mfg. Co. Ltd. Capacitance sensor apparatus of divided multi-electrode type
US5442347A (en) * 1993-01-25 1995-08-15 The United States Of America As Represented By The Administrater, National Aeronautics & Space Administration Double-driven shield capacitive type proximity sensor
US5373245A (en) * 1993-07-12 1994-12-13 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Capaciflector camera
JP2647798B2 (en) * 1993-12-27 1997-08-27 工業技術院長 Chemical / physical quantity identification method and device
US5844415A (en) * 1994-02-03 1998-12-01 Massachusetts Institute Of Technology Method for three-dimensional positions, orientation and mass distribution
US5914610A (en) * 1994-02-03 1999-06-22 Massachusetts Institute Of Technology Apparatus and method for characterizing movement of a mass within a defined space
US5802479A (en) * 1994-09-23 1998-09-01 Advanced Safety Concepts, Inc. Motor vehicle occupant sensing systems
GB9422911D0 (en) * 1994-11-14 1995-01-04 Moonstone Technology Ltd Capacitive touch detectors
US5539292A (en) * 1994-11-28 1996-07-23 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Capaciflector-guided mechanisms
US5521515A (en) * 1995-02-17 1996-05-28 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Frequency scanning capaciflector for capacitively determining the material properties
US5948031A (en) * 1996-02-23 1999-09-07 Nec Technologies, Inc. Vehicle passenger sensing system and method
US6161070A (en) * 1996-02-23 2000-12-12 Nec Home Electronics, Inc. Passenger detection system
US6275146B1 (en) 1996-04-23 2001-08-14 Philip W. Kithil Vehicle occupant sensing
US5871232A (en) * 1997-01-17 1999-02-16 Automotive Systems, Laboratory, Inc. Occupant position sensing system
US6290255B1 (en) 1997-03-07 2001-09-18 Automotive Systems Laboratory, Inc. Occupant detection system
US5964478A (en) * 1997-03-07 1999-10-12 Automotive Systems Laboratory, Inc Electric field sensing air bag danger zone sensor
US6242927B1 (en) 1997-04-09 2001-06-05 Case Corporation Method and apparatus measuring parameters of material
US6121782A (en) * 1997-04-09 2000-09-19 Case Corporation Method for measuring yield and moisture
US6220627B1 (en) 1998-04-20 2001-04-24 Automotive Systems Lab Occupant detection system
US6302438B1 (en) 1998-04-21 2001-10-16 Automotive Systems Laboratory, Inc. Occupant detection system
US6825765B2 (en) 1998-12-30 2004-11-30 Automotive Systems Laboratory, Inc. Occupant detection system
US6392542B1 (en) 1999-07-12 2002-05-21 Automotive Systems Laboratory, Inc. Occupant sensor
US6283504B1 (en) * 1998-12-30 2001-09-04 Automotive Systems Laboratory, Inc. Occupant sensor
US6348862B1 (en) 1999-03-05 2002-02-19 Automotive Systems Laboratory, Inc. Proximity sensor
US6373235B1 (en) * 1999-05-04 2002-04-16 Clifford A. Barker Apparatus and method for determining the position and motion of an object and for precise measurement of phase-related values
US6498471B2 (en) 1999-05-04 2002-12-24 A. Clifford Barker Apparatus and method for direct digital measurement of electrical properties of passive components
US6378900B1 (en) 1999-05-11 2002-04-30 Automotive Systems Laboratory, Inc. Occupant detection system
US6445294B1 (en) 1999-07-15 2002-09-03 Automotive Systems Laboratory, Inc. Proximity sensor
DE60122159T2 (en) * 2000-05-26 2007-07-05 Automotive Systems Laboratory Inc., Farmington Hills OCCUPANCY SENSOR
US6593755B1 (en) 2000-07-31 2003-07-15 Banner Engineering Corporation Method and apparatus for detection sensor shielding
US6492821B1 (en) 2000-07-31 2002-12-10 Banner Engineering Corporation Method and apparatus for detection signal processing
US6552550B2 (en) 2000-09-29 2003-04-22 Intelligent Mechatronic Systems, Inc. Vehicle occupant proximity sensor
US7256589B2 (en) 2001-04-27 2007-08-14 Atrua Technologies, Inc. Capacitive sensor system with improved capacitance measuring sensitivity
US7259573B2 (en) * 2001-05-22 2007-08-21 Atrua Technologies, Inc. Surface capacitance sensor system using buried stimulus electrode
EP1407477A4 (en) * 2001-05-22 2006-06-07 Atrua Technologies Inc Improved connection assembly for integrated circuit sensors
JP2005510394A (en) * 2001-10-31 2005-04-21 オートモーティブ システムズ ラボラトリー インコーポレーテッド Occupant detection system
AU2002353332A1 (en) 2001-12-13 2003-06-23 Intelligent Mechatronic Systems, Inc. Occupant presence detection device
US7370883B2 (en) 2002-06-03 2008-05-13 Intelligent Mechatronic Systems, Inc. Three dimensional occupant position sensor
US6891382B2 (en) * 2002-10-15 2005-05-10 Massachusetts Instiute Of Technology Three-dimensional characterization using a one-dimensional electrode array
CA2448479C (en) * 2002-11-12 2009-05-05 Makita Corporation Power tools
US6922153B2 (en) * 2003-05-13 2005-07-26 Credo Technology Corporation Safety detection and protection system for power tools
US8321173B2 (en) * 2004-08-25 2012-11-27 Wallance Daniel I System and method for using magnetic sensors to track the position of an object
US8040142B1 (en) 2006-03-31 2011-10-18 Cypress Semiconductor Corporation Touch detection techniques for capacitive touch sense systems
US8004497B2 (en) 2006-05-18 2011-08-23 Cypress Semiconductor Corporation Two-pin buttons
US8547114B2 (en) 2006-11-14 2013-10-01 Cypress Semiconductor Corporation Capacitance to code converter with sigma-delta modulator
US8164354B2 (en) 2006-11-28 2012-04-24 Process Equipment Co. Of Tipp City Proximity detection system
US8058937B2 (en) * 2007-01-30 2011-11-15 Cypress Semiconductor Corporation Setting a discharge rate and a charge rate of a relaxation oscillator circuit
US7656169B2 (en) * 2007-02-06 2010-02-02 Iee International Electronics & Engineering S.A. Capacitive occupant detection system
US9500686B1 (en) 2007-06-29 2016-11-22 Cypress Semiconductor Corporation Capacitance measurement system and methods
US8570053B1 (en) 2007-07-03 2013-10-29 Cypress Semiconductor Corporation Capacitive field sensor with sigma-delta modulator
US8169238B1 (en) 2007-07-03 2012-05-01 Cypress Semiconductor Corporation Capacitance to frequency converter
US8525798B2 (en) 2008-01-28 2013-09-03 Cypress Semiconductor Corporation Touch sensing
US8358142B2 (en) 2008-02-27 2013-01-22 Cypress Semiconductor Corporation Methods and circuits for measuring mutual and self capacitance
US8319505B1 (en) 2008-10-24 2012-11-27 Cypress Semiconductor Corporation Methods and circuits for measuring mutual and self capacitance
US9104273B1 (en) 2008-02-29 2015-08-11 Cypress Semiconductor Corporation Multi-touch sensing method
US20090231764A1 (en) * 2008-03-14 2009-09-17 Cooper Technologies Company Capacitor Bank Monitor and Method of use Thereof
US8321174B1 (en) 2008-09-26 2012-11-27 Cypress Semiconductor Corporation System and method to measure capacitance of capacitive sensor array
US8476912B2 (en) * 2010-03-04 2013-07-02 Franklin Sensors, Inc. Obscured feature detector and method
US8791708B2 (en) * 2010-03-04 2014-07-29 Franklin Sensors Inc. Obscured feature detector with advanced trace properties
US8593163B2 (en) * 2010-03-04 2013-11-26 Franklin Sensors, Inc. Surface-conforming obscured feature detector
US9939932B2 (en) * 2014-03-21 2018-04-10 Advanced Sensor Technology Limited Position sensing device and method using self-capacitance
EP2922205B1 (en) 2014-03-21 2020-12-23 Melius SA Position sensing device and method using self-capacitance

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4190797A (en) * 1978-03-31 1980-02-26 Gould Inc. Capacitive gauging system utilizing a low internal capacitance, high impedance amplifier means
US4908574A (en) * 1986-09-03 1990-03-13 Extrude Hone Corporation Capacitor array sensors for determining conformity to surface shape
US4888824A (en) * 1988-10-05 1989-12-19 Emhart Industries Inc. Glass container wall thickness inspecting machine
US5049824A (en) * 1988-12-12 1991-09-17 Mitutoyo Corp. Phase discrimination type electrostatic capacity detector
US4918376A (en) * 1989-03-07 1990-04-17 Ade Corporation A.C. capacitive gauging system
US4958129A (en) * 1989-03-07 1990-09-18 Ade Corporation Prealigner probe
US5097216A (en) * 1990-10-09 1992-03-17 Agr International, Inc. Apparatus for inspecting the wall thickness of a container and corresponding method
US5166679A (en) * 1991-06-06 1992-11-24 The United States Of America As Represented By The Administrator Of The National Aeronautics & Space Administration Driven shielding capacitive proximity sensor
US5184082A (en) * 1991-09-18 1993-02-02 Honeywell Inc. Apparatus and method for testing an active matrix pixel display

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0838737A1 (en) * 1996-10-25 1998-04-29 Asulab S.A. Means for identifying a manual action on a surface, in particular for a time piece
FR2755269A1 (en) * 1996-10-25 1998-04-30 Asulab Sa DEVICE FOR IDENTIFYING A MANUAL ACTION ON A SURFACE, ESPECIALLY FOR A WATCHMAKING PIECE
US6184871B1 (en) 1996-10-25 2001-02-06 Asulab S.A. Identification device of a manual action on a surface, in particular for a timeplace
EP0984329A2 (en) * 1998-09-04 2000-03-08 Canon Kabushiki Kaisha Position detection apparatus having a plurality of detection sections, and exposure apparatus
EP0984329A3 (en) * 1998-09-04 2002-05-02 Canon Kabushiki Kaisha Position detection apparatus having a plurality of detection sections, and exposure apparatus
US6529263B2 (en) 1998-09-04 2003-03-04 Canon Kabushiki Kaisha Position detection apparatus having a plurality of detection sections, and exposure apparatus
US7072023B2 (en) 1998-09-04 2006-07-04 Canon Kabushiki Kaisha Position detection apparatus having a plurality of detection sections, and exposure apparatus
WO2003106936A2 (en) * 2002-06-13 2003-12-24 Environment One Corporation Scanning capacitive array sensor and method
WO2003106936A3 (en) * 2002-06-13 2004-06-17 Environment One Corp Scanning capacitive array sensor and method

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